Wisconsin has one of the worst flu vaccination rates in the nation for adults ages 18 to 64 — a group hit especially hard this flu season, according to an analysis released Tuesday by Trust for America's Health.

This group of young and middle-age adults accounts for nearly 80% of all flu-related hospitalizations since October in Milwaukee.

Fewer than one in three in that age range (31.9%) got shots last flu season in Wisconsin, ranking the state 47th nationwide. Wisconsin is one of three states that saw declines in vaccination rates for young and middle-age adults from the 2011-'12 to the 2012-'13 season, according to the Trust For America's Health analysis. Florida and Kansas were the other two states.

State numbers so far this flu season reflect a continuing pattern of low vaccination rates among younger adults who most years don't end up hospitalized in great numbers.

"Yes, we have to be cognizant that we're not meeting our target for the citizenry of Wisconsin being protected" from influenza, said Dan Hopfensperger, director of the Wisconsin Immunization Program.

While state and local health departments must continue to put the word out about the importance of flu shots, he said, residents also "must avail themselves of vaccine and take the time to get it."

Lower vaccination rates among young adults may be partially attributed to them not having a primary caregiver because they are otherwise healthy, Hopfensperger said.

Young and middle-aged adults also tend to underestimate the potential seriousness of influenza at their age, he said, and assume they may only have to miss a few days of work because they're ill. They may not take time to get a flu shot, even if they're in a pharmacy that offers convenient shots, he said.

As of Jan. 9, only about 15% of Wisconsin adults ages 18 to 24 had received flu shots. The rate was slightly better — 20% — for those ages 25 to 49. And not surprisingly, it was even better — 35% — for adults ages 50 to 64, according to data collected from sites that report to the Wisconsin Immunization Registry. More than 60% of adults ages 65 and older had flu shots as of Jan. 9.

Wisconsin's overall flu vaccination rate — essentially everyone over age 6 months — isn't much better than its rate for young and middle-age adults. The state ranked No. 44 nationwide last flu season, with total coverage of 40.6%. That was a decrease from the year before.

Vaccine still available

Public health officials are encouraging those who haven't gotten a flu shot to get one now. It takes two weeks to build full immunity after receiving the shot, but the vaccine can help prevent the flu or at least reduce its symptoms.

Twenty-one Milwaukee area residents showed up for free flu shots Tuesday afternoon at St. Vincent De Paul, 2628 N. King Drive. That's barely one-fifth of the number of shots that were available. The shots were courtesy of Molina Healthcare and Walgreens.

Mark Zimmerman, 50, of West Allis went to the site because he lost his health insurance recently when he was laid off.

"I'm 50 and I don't want to get the flu," said Zimmerman, adding he normally gets a flu shot every year. He said he was aware that this flu season had been particularly rough for middle-age adults.

Alivia Jackson, 18, said she got a flu shot because she knows the virus is going around now. Jackson, a freshman at the University of Wisconsin-La Crosse, also knows how serious the flu can be.

The Milwaukee teen said she missed her eighth-grade graduation in 2009 because she had H1N1 swine flu.

Molina Healthcare and Walgreens will offer more free flu shots on a first come, first served basis starting at 4:30 p.m. Wednesday at the St. Vincent De Paul at 931 W. Madison St. The first 50 people will receive shots; the next 50 will be given vouchers for a free shot at a Walgreens store.

"There is still an ample supply of vaccine in the community," Sarah DeRoo, spokeswoman for the Milwaukee Health Department, said Tuesday afternoon — countering some media reports of shortages.

A few individual pharmacies may have used up their season's supply of flu vaccine, but Hopfensperger said he hasn't heard of any shortages from manufacturers or Wisconsin communities.

Hospitalizations high

Hospitalizations among young and middle-age adults in Milwaukee are the highest since the 2009 pandemic — 67% higher than last flu season, according to Paul Biedrzycki, director of disease control and environmental health for the Milwaukee Health Department.

This season's dominant flu strain, H1N1 (swine flu), was first detected in 2009. It hit the young especially hard that year, too.

Milwaukee, as of Jan. 4, recorded about 25% (142) of Wisconsin's total flu hospitalizations.

There's also been an increase in ICU admissions and those needing mechanical ventilation in the 19- to 64-year-old age group, Biedrzycki said. That age group now makes up approximately 19% of all ICU admissions; 7% of hospitalizations within this age group required mechanical ventilation, he said.

"The trend of low vaccination rates among younger adults is particularly troubling this year, when they are more at risk than usual for the effects of the H1N1 strain of flu that's circulating," said Jeffrey Levi, executive director of Trust For America's Health, a nonpartisan, nonprofit organization based in Washington, D.C., that is dedicated to improving public health and disease prevention.

"It's easy to become complacent about the flu. We're used to it, it happens every year. So much so that we forget that it is largely preventable through a quick shot, which I might add is now free to most Americans thanks to the Affordable Care Act," Levi said.

The flu isn't just an uncomfortable inconvenience, it is deadly and costly, Levi said. Millions of Americans do not have paid sick leave, so they either go to work sick — infecting others — or do not get paid, he said.